Germany and other European Union countries turned a blind eye to the refugee crisis building on its external borders for too long, Chancellor Angela Merkel said in a German newspaper interview to be published on Wednesday.

Merkel, who has faced criticism in Germany for launching her policies of welcoming refugees a year ago, also told the Sueddeutsche Zeitung that Germany and the EU will need patience and endurance in dealing with migration of people to Europe.

"There are political issues that one can see coming but don't really register with people at that certain moment - and in Germany we ignored both the problem for too long and blocked out the need to find a pan-European solution," she said.

Merkel made the comments in an unusually self-critical analysis that appeared to be timed to the one-year anniversary on Wednesday of her now-famous statement "wir schaffen das", or "we can do this", when asked about the rising tide of refugees.

"The deal with Turkey is as sordid as anything I have ever seen in
modern European politics. On the day that EU leaders signed the deal,
Recep Tayyip Erdogan, the Turkish president, gave the game away:
'Democracy, freedom and the rule of law.... For us, these words have
absolutely no value any longer.' At that point the European Council
should have ended the conversation with Ahmet Davutoglu, the Turkish
prime minister, and sent him home. But instead, they made a deal with
him — money and a lot more in return for help with the refugee crisis."

Turkey has threatened to renege on a landmark deal to curb illegal
migration to the European Union if the bloc fails to grant visa-free
travel to Europe for Turkey's 78 million citizens by the end of June.

If Ankara follows through on its threat, it would reopen the
floodgates and allow potentially millions of migrants from Africa, Asia
and the Middle East to flow from Turkey into the European Union.